189 Novel stability and control problems of aerospace planes

This paper gives a general survey of the behaviour of surface vessels subjected to accelerations in a horizontal plane. There are two different cases which frequently occur in combination but which, for convenience, are treated separately. First, longitudinal acceleration is considered, including positive or negative acceleration in the fore and aft plane; problems of stability and manoeuvrability and means of improving directional control are discussed. Next, the manoeuvring problem associated with transverse accelerations is described, with particular emphasis on the use of auxiliary devices, such as side thrusters, and modified propulsive arrangements. Finally, the influences of currents, winds and restricted depth on manoeuvrability are outlined.

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Manoeuvring and Seakeeping Aspects of Pod-Driven Ships

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1243/147509005x10495 ◽

2005 ◽

Vol 219 (2) ◽

pp. 77-91 ◽

Cited By ~ 2

Author(s):

Z Ayaz ◽

O Turan ◽

D Vassalos

Keyword(s):

Numerical Code ◽

Ship Motions ◽

Control Problems ◽

Stability And Control ◽

Pull Out ◽

Hull Forms ◽

Six Degree Of Freedom ◽

And Control ◽

Hydrodynamic Optimization ◽

Equations Of Motions

An existing coupled non-linear six-degree-of-freedom model, which combines manoeuvring and seakeeping, is being enhanced for the simulation of motions of azimuthing pod-driven vessels. The equations of motions and modified numerical model for calculation of pod-induced propulsive and hull forces are presented. The modified numerical code has been verified using an extensive amount of experimental data for both conventional and pod-driven roll-on roll-off passenger ship/ferry (ROPAX) hull forms. Comparisons have been made between conventional and podded control using zigzag and pull-out manoeuvring tests and significant motion amplitudes in waves, with the aim of investigating the directional stability and course-keeping ability of pod-driven ships, as well as the effect of large pod-induced heel angles to the turning and ship motions in waves. The results showed satisfactory agreement with experiments for the enhanced model. In the light of this investigation, the importance of hydrodynamic optimization for the azimuthing pod-driven ship design to eliminate any stability and control problems caused by design modifications has been demonstrated by the use of numerical simulations. Finally the efficiency of the azimuthing podded drives, in terms of overall controllability and seakeeping characteristics of ships, is discussed and conclusions are drawn.

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